The present invention relates to the delivery of stents. A stent is a type of endoprosthesis device, typically intraluminally placed or implanted within a vein, artery, or other tubular body organ for treating an occlusion, stenosis, aneurysm, collapse, dissection, or weakened, diseased, or abnormally dilated vessel or vessel wall, by expanding the vessel or by reinforcing the vessel wall. In particular, stents are quite commonly implanted into the coronary, pulmonary, neurovascular, peripheral vascular, renal, gastrointestinal and reproductive systems, in order to reinforce individual body organs. The invention described herein is particularly useful for deploying stents in bifurcations, and is therefore described below with respect to this application.
In vessel bifurcations, a main vessel splits into two branch vessels. Implanting stents in bifurcations is particularly problematic because of the need to precisely locate the stent both longitudinally and radially in the bifurcation. This is especially the case when the stent is designed with a side opening which is to face the ostium of the branching vessel. One technique for precisely locating the stent is by initially introducing two guidewires into the main vessel, one guidewire extending through the bifurcation into one branch vessel, and the other guidewire extending through the bifurcation into the other branch vessel, and then using the two guidewires for guiding the stent, which is mounted on a delivery device, e.g., a balloon angioplasty catheter, to its precise longitudinal position and radial orientation before deploying the stent. One such technique involving the initial placement of two guidewires is described, for example, in U.S. Pat. No. 5,749,825 to Fischell et al.
However, in such a two-wire technique, due to the tortuosity of the vascular system, the physician must torque the delivery system in order to deliver the guidewires to their correct location. Because of this torquing, the two guidewires frequently tend to cross over one another and/or entangle during their use for guiding the stent delivery device. Such an entanglement or crossover, if it should occur, may result in an inability of the device to be delivered by the physician, requiring the procedure to be started anew.
There is thus a widely recognized need for, and it would be highly advantageous to have, a method for delivering stents to bifurcations devoid of the above limitations.